The invention relates to a system for recording and/or reproducing signals on a magnetic medium, the system comprising a tape cassette provided with a magnetic tape and an apparatus for cooperation with the tape cassette, which apparatus has a magnetic head comprising at least one magnetoresistive element having an easy axis of magnetisation and a defined direction of magnetisation extending at least substantially parallel to said axis.
Such a system is known from EP-A-0,406,943 (which corresponds to U.S. Ser. No. 059,720 filed May 10, 1993; herewith incorporated by reference).
The known system, which employs magnetic-tape cassettes for recording digital audio signals, is now generally referred to as the DCC (Digital Compact Cassette) system. A DCC tape cassette comprises a housing having two plane-parallel main walls interconnected by transverse walls, one of which constitutes a cassette front wall with a central opening. The housing accommodates two reels with a magnetic tape extending along the central opening. The DCC tape cassette further comprises a sliding cover which is movable between a closed position and an open position and which closes the central opening in the closed position and exposes said opening in the open position.
The known system includes apparatuses suitable for cooperation with DCC tape cassettes. Such an apparatus has a magnetic head suitable for recording and/or reading information in digital form in longitudinal tracks on a magnetic tape. Recording and reading information in digital form has many advantages; for example, the signal is not afflicted with tape noise. Moreover, the frequency range is larger than in the case that information is recorded on and/or read from a magnetic tape in analog form, which results in the signal itself being also improved. The magnetic head used has a head face for the longitudinal guidance of a magnetic tape and has a read section for reading the information from the magnetic tape. For reading the information, which is present on the magnetic tape in a plurality of tracks and with different wavelengths, the read section comprises a plurality of magnetoresistive elements. The magnetic head is preferably constructed as a thin-film magnetic head and is shown, for example, in the magazine Funkschau, no. 9, Apr. 16, 1992, pp. 30-39 (herewith incorporated by reference). The magnetoresistive elements may be of a type as described in U.S. Pat. No. 4,052,748 (herewith incorporated by reference).
Each magnetoresistive element has an elongate active part of a magnetically anisotropic material, whose ends can be connected to a current or voltage source. The magnetoresistive element has an easy axis of magnetisation which coincides or substantially coincides with the longitudinal axis of said part and one defined direction of magnetisation which extends at least substantially parallel to the easy axis of magnetisation. For a correct operation of the magnetic head, in particular in the read mode, it is essential that the magnetisation in the defined direction is maintained. However, it has been found that the magnetisation thus established may be disturbed as a result of external influences, such as for example the presence of an external magnetic field or the temporary exposure to high temperatures, which may lead to a deterioration of the performance of the magnetic head.